Feeding ecology and foraging behaviour of the Namib Desert golden mole, Eremitalpa granti namibensis (Chrysochloridae)

Abstract

Eremitalpa granti namibensis is a small, blind insectivorous mole endemic to the sand dunes of the Namib Desert. Unlike most other subterranean mammals, E. g. namibensis lacks a permanent burrow system and forages for its prey on the dune surface at night. This study examines the natural dietary habits and foraging behaviour of E. g. namibensis in relation to resource abundance and distribution in the Namib dunes. Stomach content analysis revealed termites as the major dietary item with other invertebrates being of only minor importance. Biomass of potential prey items was found to be low and food resources patchily distributed. It is suggested that desert moles opportunistically exploit a sedentary prey resource which occurs in patches of high concentrations, hence avoiding the energetic costs implicit in pursuing more mobile prey. Qualitative and quantitative descriptions of nocturnal foraging paths were undertaken so that searching behaviour could be related to the variation and distribution of food items. It is concluded that movement patterns of moles are effective in encountering localized areas of high prey concentrations and in minimizing energy expenditure in an energy‐sparse environment.

Energetics of burrowing, running, and free‐living in the Namib Desert golden mole (Eremitalpa namibensis)

“…The gross cost of burrowing is about 26 times higher than the cost of running (Table 2), so total reliance on burrowing is energetically possible only in areas of high prey abun-dance, where total foraging distances are short. At another site, the`Far East', where vegetation, and presumably food, was more abundant than at Gobabeb, the tracks were even shorter, with a mean of about 62 m and a maximum less than 200 m (Fielden et al, 1990a). In 1996, the mean length was 1412 m (CI = 424); and the longest was 2300 m. In 1984, the mean track length of 19 moles was 290 m (CI = 94) and the longest track was only 695 m (Fielden et al, 1992).…”

“…The site lies at the northern extremity of the sand sea of the Namib Desert and is 1 of 2 sites used by Fielden et al (1989Fielden et al ( , 1990aFielden et al ( , b, c, 1991Fielden et al ( , 1992. The site lies at the northern extremity of the sand sea of the Namib Desert and is 1 of 2 sites used by Fielden et al (1989Fielden et al ( , 1990aFielden et al ( , b, c, 1991Fielden et al ( , 1992.…”

“…Fielden et al (1990a) obtained stomach contents of the moles and found that about half of the diet was termites (Psammotermes allocercus silvestri ) and the other half was mainly insect larvae. Fielden et al (1990a) obtained stomach contents of the moles and found that about half of the diet was termites (Psammotermes allocercus silvestri ) and the other half was mainly insect larvae.…”

“…Yet, the Namib dunes support a remarkably diverse assemblage of unusual species. Foraging behaviour comprises running over the surface of the sand, periodically`dipping' below the surface (presumably to sense the presence of food), and more extensive under-sand burrowing in areas containing high concentrations of food (Fielden, Perrin & Hickman, 1990a). This solitary, 20-g insectivore belongs to the endemic southern African family of golden moles (Chrysochloridae).…”

Risk-sensitive foraging behaviour of the round-eared elephant shrew (Macroscelides proboscideus)

“…When given together the elephant shrews would eat all mealworms first. Mealworms, a food high in protein and readily assimilable energy (Fielden et al 1990), were used in experiments because we considered that the elephant shrews would be more sensitive to variance in a resource more critically linked to reproduction and survival than herbage (cf. Kerley 1989).…”